Structure of clay minerals of road soil-cement during complex modification

Abstract

Previously obtained positive results of studies of physical, mechanical, technological and operational properties of road soil-cement at their complex multifunctional modification with organosilicon compounds and polycarboxylate superplasticizers have shown the effectiveness of the use of strengthened soils in the construction of roads. However, the influence of complex modification on changes in the structure of clay minerals of strengthened soils in road construction remains insufficiently studied. Using X-ray phase analysis, comprehensive studies of the structure of modified clay minerals were carried out to reveal intercalation processes and changes in the size of their particles as a result of splitting processes. Chemical structure of the studied modifiers, nature of their interaction with clay minerals and organomineral bonds were confirmed using IR spectroscopy. The combined influence of modifying effect of dodecyltriethoxysilane and polycarboxylate ester on kaolinite and montmorillonite clays was established, which led to the manifestation of synergistic mechanism at strengthening of clay soils. During the modification, a multifunctional effect was noted, characterized by an increase of integral intensity of diffraction maxima on the diffraction patterns of modified clay soils, associated with an increase of interplanar distances in their structure as a result of intercalation processes. The positive effect of complex modification of clays is associated with splitting and reduction of mineral particle sizes. It has been established that the consequence of complex modification is chemical interaction (chemisorption) with the formation of organosilane bonds, which provide increased efficiency in strengthening of clay soils in road construction.

Keywords

• kaolinite
• montmorillonite
• dodecyltriethoxysilane
• complex modification
• polycarboxylate ester
• intercalation
• splitting
• chemisorption
• soil-cement